Canada thistle, the plague of my peonies

– Posted in: Pests, Plagues, and Varmints

Canada thistle weaves throughout the peony bedObservant readers may have noticed the prickly-leaved weed sidling up to 'Rozella' in my last post. That dastardly villain is Canada thistle, aka Cirsium arvense, and it is one nasty customer. According to the University of California Cooperative Extension, Once established, Canada thistle spreads rapidly by horizontal roots, up [...]